Decorative coating compositions

ABSTRACT

A coating composition includes water, a plurality of flakes having a maximum dimension less than 0.05 inches, a plurality of inorganic fibers, a thixotropic suspending agent that is insoluble in water, and a resin. Decorative coating on a concrete substrate is also provided.

TECHNICAL FIELD

The present invention relates to a decorative coating composition forconcrete substrates.

BACKGROUND

Hard surfaces made from materials such as concrete are ubiquitous. Thesesurfaces are found in many industrial and home environments. Forexample, cement and concrete surfaces are found in most industrialshops, garages, sidewalks, and the like. Over time, the appearance ofthese surfaces degrades due to staining and contamination from theenvironment.

Decorative coatings for concrete and cement surfaces are known. A typeof decorative coating for these applications includes a plurality ofcolored flakes dispersed in resinous layers. Most prior art coatingprocesses involve applying a resin to the surface and then introducingflakes or flecks (i.e., broadcasting) over the applied layer before ithas dried. The coated layer is then over-coated with one or moreadditional resinous layers to ensure that the flakes are not exposed.Exposure of the flakes leads to an undesirable appearance over time aswell as premature failure of the coating. Although this process worksreasonably well, the multiple steps necessary for applying such layersmake the process complicated and tedious.

Accordingly, there is a need for improved methods and compositions forcoating hard surfaces.

SUMMARY

The present invention solves one or more problems of the prior art byproviding, in at least one embodiment, compositions that are suitablefor coating concrete. The coating composition includes water, aplurality of flakes having a maximum dimension less than 0.05 inches, aplurality of inorganic fibers, a thixotropic suspending agent that isinsoluble in water, and a resin.

In another embodiment, a coated substrate formed from the coatingcomposition is provided. The coated substrate includes a substrate witha decorative layer disposed over the substrate. The decorative layerincludes a resin, a plurality of flakes having a maximum dimension lessthan 0.05 inches dispersed within the resin, and a plurality ofinorganic fibers dispersed within the resin. In a refinement, thedecorative layer is not over-coated with any other resinous layers.

In still another embodiment, a method for forming the coated substrateincludes a step of applying the coating composition set forth above to asubstrate. The coating composition is allowed to cure to form the coatedsubstrate. Advantageously, this method does not involve broadcasting theflakes to a wet resinous pre-layer while avoiding additional over-coatlayers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic cross section of a substrate coated with adecorative layer; and

FIG. 2 provides a table comparing a composition of the invention tocommercial coatings.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferredcompositions, embodiments and methods of the present invention whichconstitute the best modes of practicing the invention presently known tothe inventors. The Figures are not necessarily to scale. However, it isto be understood that the disclosed embodiments are merely exemplary ofthe invention that may be embodied in various and alternative forms.Therefore, specific details disclosed herein are not to be interpretedas limiting, but merely as a representative basis for any aspect of theinvention and/or as a representative basis for teaching one skilled inthe art to variously employ the present invention.

Except in the examples, or where otherwise expressly indicated, allnumerical quantities in this description indicating amounts of materialor conditions of reaction and/or use are to be understood as modified bythe word “about” in describing the broadest scope of the invention.Practice within the numerical limits stated is generally preferred.Also, unless expressly stated to the contrary: percent, “parts of,” andratio values are by weight; the description of a group or class ofmaterials as suitable or preferred for a given purpose in connectionwith the invention implies that mixtures of any two or more of themembers of the group or class are equally suitable or preferred;description of constituents in chemical terms refers to the constituentsat the time of addition to any combination specified in the descriptionand does not necessarily preclude chemical interactions among theconstituents of a mixture once mixed; the first definition of an acronymor other abbreviation applies to all subsequent uses herein of the sameabbreviation and applies mutatis mutandis to normal grammaticalvariations of the initially defined abbreviation; and, unless expresslystated to the contrary, measurement of a property is determined by thesame technique as previously or later referenced for the same property.

It is also to be understood that this invention is not limited to thespecific embodiments and methods described below, as specific componentsand/or conditions may, of course, vary. Furthermore, the terminologyused herein is used only for the purpose of describing particularembodiments of the present invention and is not intended to be limitingin any way.

It must also be noted that, as used in the specification and theappended claims, the singular form “a,” “an,” and “the” comprise pluralreferents unless the context clearly indicates otherwise. For example,reference to a component in the singular is intended to comprise aplurality of components.

Throughout this application, where publications are referenced, thedisclosures of these publications in their entireties are herebyincorporated by reference into this application to more fully describethe state of the art to which this invention pertains.

The term “aspect ratio” as used in at least one embodiment refers to theratio of the minimum and maximum dimensions of a particle. In arefinement, the aspect ratio is the ratio of the minimum and maximumFeret diameters of a particle. For example, the aspect ratio of acircular particle is 1. The aspect ratio for a flat particle such as aflake has low numbers less than 0.2 and can approach zero ifsufficiently thin.

The term “Feret diameters” as used in at least one embodiment refers tothe distance between two tangents parallel to the opposite sides of aparticle.

The term “residue” as used in at least one embodiment refers to thatportion of a chemical compound that remains in a layer after dryingand/or curing takes place to form these dried layers.

The term “dominant wavelength” refers to a way of describingpolychromatic light mixtures in terms of monochromatic light that evokesan identical perception of hue. It is determined on the CIE colorcoordinate space by straight line the color coordinates for the color ofinterest and the coordinates for the illuminate. The intersection at theperimeter of the coordinate space nearest the color of interest is thedominant wavelength.

In an embodiment, a coating composition suitable for applying adecorative coating on a hard surface is provided. Examples of such hardsurfaces include, but are not limited to, concrete, granite, and cementsurfaces. The coating composition includes water, a plurality of flakeshaving a maximum dimension less than 0.05 inches, a plurality ofinorganic fibers, a thixotropic suspending agent that is insoluble inwater, and a resin. Typically, the plurality of flakes includes opaqueflakes, and in particular, colored flakes.

In the context of the present invention, the term “flakes” refers tosubstantially flat particles having two dimensions that are of similarextent and a third dimension that is much smaller. As used herein theterms “flakes” and “flecks” are interchangeable. The flakes have amaximum dimension less than 0.05 inches. The maximum dimension is thelongest dimension of the flake and is sometimes referred to as thelength. In a refinement, the flakes have a maximum dimension less than,in increasing order of preference, 0.05 inches, 0.04 inches, 0.03inches, 0.02 inches, or 0.01 inches on average. In a refinement, theflakes have a maximum dimension greater than, in increasing order ofpreference, 0.001 inches, 0.005 inches, 0.007 inches, 0.01 inches, or0.012 inches on average. Characteristically, the flakes are opaque andare colored. In particular, the flakes have a dominant wavelength in thevisible region of the electromagnetic spectrum (i.e., a wavelength oflight from 390 to 700 nm). In a variation, a majority or more (>50number percent) of the flakes in the plurality of flakes have an aspectratio (e.g., thickness to length) less than 1:5 and greater than 0:1. Ina refinement, a majority or more (>50 number percent) of the flakes inthe plurality of flakes have an aspect ratio less than 1:5, 1:10, 1:20;1:50; or 1:100. In another refinement, a majority or more (>50 numberpercent) of the flakes in the plurality of flakes have an aspect ratiogreater than 1:2000, 1:1000, 1:500; 1:10; or 1:50. Suitable coloredflakes include polymeric resins, inorganic particles, and pigment. Anexample of colored flakes are the Polymer ColorFlakes™ commerciallyavailable from Torginol, Inc. located in Sheboygan, Wis.

In some refinements, the plurality of flakes is present in an amountgreater than, in increasing order of preference, 1 weight percent, 2weight percent, 5 weight percent, 10 weight percent, 15 weight percent,or 20 weight percent of the total weight of the coating composition. Inother refinements, plurality of flakes is present in an amount lessthan, in increasing order of preference, 60 weight percent, 55 weightpercent, 50 weight percent, 45 weight percent, 40 weight percent, 30weight percent, or 25 weight percent of the total weight of the coatingcomposition.

The present invention includes a suspending agent, and in particular, athixotropic suspending agent. The term “suspending agent” means acomponent that maintains components in the coating composition dispersedthereby delaying the time it takes for the flakes and other waterinsoluble components from settling. In one variation, the suspendingagent includes magnesium silicate, and in particular, a hydratedmagnesium silicate. Examples of useful hydrated magnesium silicates havechemical formulae Mg₈Si₁₂O₃₀(OH)₄(OH₂)₄.8H₂O or Mg₄Si₆O₁₅(OH)₂.6H₂O. Ina refinement, the suspending agent includes needle-shaped particleshaving a length from about 1 to 5 microns and a surface area from about100 to 500 m²/gram. An example of such needle shaped particles includessepiolite clay. Sepiolite is a clay mineral of magnesium silicate. Atypical formula for sepiolite clay is Mg₄Si₆O₁₅(OH)₂.6H₂O. A specificexample of a useful suspending agent include ATTAGEL™ commerciallyavailable from BASF Corporation located in Wyandotte Mich.; PANGEL™Rheology Modifiers commercially available from ISCA UK LTD located inNewport United Kingdom; and LAPONITE™ commercially available from ALTANAAG located in Wesel Germany.

In a refinement, the plurality of flakes is present in an amount of 0.2to 4 weight percent of the total weight of the coating composition. Insome refinements, the suspending agent is present in an amount greaterthan, in increasing order of preference, 0.5 weight percent, 0.1 weightpercent, 0.2 weight percent, 0.3 weight percent, 0.5 weight percent, or1 weight percent of the total weight of the coating composition. Inother refinements, the suspending agent is present in an amount lessthan, in increasing order of preference, 10 weight percent, 8 weightpercent, 5 weight percent, 4 weight percent, 3 weight percent, or 2.5weight percent of the total weight of the coating composition.

As set forth above, the coating composition includes a resin. Typically,the resin includes at least one acrylic resin. It should be appreciatedthat the acrylic resins used herein are often obtained and introducedinto the coating composition as aqueous emulsions. . In some refinementsthe acrylic resins are copolymer and/or are cross-linked. Examples ofuseful resins includes CRILAT™ 4815 commercially available from Vinavil,SpA located in Milano Italy and EPS® 2293 commercially available fromEPS materials located in Marengo Ill. The following amounts for theresin are provided in terms of the actual amounts of resin (e.g.,solids) in the composition. In a refinement, the resin is present in anamount from about 10 to 70 weight percent with the balance being water.In some refinements, the resin is present in an amount greater than, inincreasing order of preference, 5 weight percent, 8 weight percent, 10weight percent, 12 weight percent, 15 weight percent, or 20 weightpercent of the total weight of the coating composition. In otherrefinements, the resin is present in an amount less than, in increasingorder of preference, 60 weight percent, 50 weight percent, 40 weightpercent, 45 weight percent, 30 weight percent, or 25 weight percent ofthe total weight of the coating composition.

As set forth above, the coating composition also includes a plurality ofinorganic fibers. Suitable inorganic fibers include metal oxides such assilicon oxide, aluminum oxide, CaO+MgO, and the like, and combinationsthereof. In a refinement, the inorganic fibers have an average lengthfrom about 50 to 800 microns and an average diameter from about 1 to 10microns. An example of a useful inorganic fiber is CoatForce® CF30commercially available from Lapinus Fibres located in The Netherlands.In one refinement, the inorganic fibers are present in an amount fromabout 0.5 to 5 weight percent of the total weight of the composition. Insome refinements, the inorganic fibers are present in an amount greaterthan, in increasing order of preference, 0.1 weight percent, 0.3 weightpercent, 0.5 weight percent, 0.8 weight percent, 1.0 weight percent, or2.0 weight percent of the total weight of the coating composition. Inother refinements, the inorganic fibers are present in an amount lessthan, in increasing order of preference, 15 weight percent, 10 weightpercent, 8 weight percent, 5 weight percent, 4 weight percent, or 3weight percent of the total weight of the coating composition.

Certain variations of the coating composition include one or moreadditional additives selected from the group consisting of pigments,solvents, thickeners, surfactants, defoamers, preservatives, buffers,and combinations thereof. The total amount of additives is present in anamount from about 0.1 to 20 weight percent of the total weight of thecoating composition. In a refinement, the total amount of additives ispresent in an amount from about 0.1 to 10 weight percent of the totalweight of the coating composition. In another refinement, each additivewhen present is independently present in an amount greater than 0.01weight percent, 0.03 weight percent, 0.05 weight percent, 1 weightpercent, 2.0 weight percent, or 3.0 weight percent of the total weightof the coating composition. In still another refinement, each additivewhen present is independently present in an amount less than 15 weightpercent, 10 weight percent, 5.0 weight percent, 3.0 weight percent, 2.0weight percent, or 1.0 weight percent of the total weight of the coatingcomposition.

Specific examples of suitable dispersant include Tetrapotassiumpyrophosphate (TKPP) and potassium tripolyphosphate (KTPP). Additionalexamples include TAMOL™ 2011, TAMOL™ 731a, TAMOL™ 2002, and TAMOL 1981124 commercially available from The Dow Chemical Company located inMidland Mich. Specific examples of suitable thickeners include SCT 275,RM8W, RM12W, RM 895, and RM 825commercially available from The DowChemical Company located in Midland Michigan. Specific examples ofsuitable surfactants include TERGITOL™ NP-9, TRITON™ X405, TRITON™ CF-10commercially available from the Dow Chemical Company located in MidlandMich. Specific examples of suitable solvents propylene glycol,triethylene glycol, TEXANOL™ commercially available from EastmanChemical Company located in Kingsport Tenn., and BUTYL CELLOSOLVE™ (e.g.ethylene glycol monobutyl ether) commercially available from The DowChemical Company located in Midland Mich. Specific examples of suitabledefoamers includes BYK 22 and BYK 024 commercially available from ALTANAAG located in Wessel Germany; DREW™ T-4507 and DREW™ L-475 commerciallyavailable from Ashland, Inc.; TEGO™ 810 commercially available fromEvonik Industries AG located in Essen, North Rhine-Westphalia, Germany;and FOAMSTAR™ A12 commercially available from BASF corporation locatedin Wyandotte Mich.

As set forth above, the coating composition may also include variouspigments to impart additional properties as desired. For example glow inthe dark, metallic, infrared reflecting, and colored pigments can beadded. Moreover, pigments can be added to improve scuff resistance.

The balance of the coating composition is water. Clearly, the sum of allthe components of the coating composition totals to 100 percent.Typically, water is present in an amount from about 10 to 30 weightpercent. In some refinements, water is present in an amount from about 5to 50 weight percent of the coating composition.

In another embodiment, a coated substrate formed from the coatingcomposition set forth above is provided. With reference to FIG. 1, aschematic cross section of a coated substrate is provided. Coatedsubstrate 10 includes substrate 12 with a decorative layer 14 disposedover the substrate. Decorative layer 14 includes a resin 16, a pluralityof flakes 18 having a maximum dimension less than 0.05 inches dispersedwithin the resin, and a plurality of inorganic fibers 20 dispersedwithin the resin. Characteristically, the decorative layer is notover-coated with any other resinous layers. The coated substrate isformed applying the coating composition set forth above to a substrate.The coating composition is allowed to cure to form the coated substrate.Advantageously, this method does not involve broadcasting the flakes toa wet resinous pre-layer. Moreover, the present method avoids usingadditional over-coat layers.

The following examples illustrate various embodiments of the presentinvention. Those skilled in the art will recognize many variations thatare within the spirit of the present invention and scope of the claims.

Table 1 provides an example of a coating composition is useful forforming a decorative layer on a concrete or cement substrate. Theresulting decorative coating are categorized by variously standard testmethods. For example, gloss can be determined by test methods set forthin ASTM D523 and ASTM D823; adhesion (Cross hatch) can be determined bytest methods set forth in ASTM D3359; chemical resistance can bedetermined by test methods set forth in ASTM D1308; and coefficient offriction (James Test) can be determined by test methods set forth inASTM D4103, ASTM F489, and ASTM 2047. Table 2 in FIG. 2 provides acomparison of the composition with several commercially availablecoating systems. A composition of the present invention is observed toprovide an overall superior performance to all of the commercialprocesses that were tested. The improved stain/chemical resistance,water resistance and adhesive properties are observed to besignificantly improved.

TABLE 1 Coating composition Ingredient Range (%). water 10.0-20.0Polymeric Pigment 0.05-3.0  Dispersant Surfactant/Defoamer 0.05-2.0 Acetylene Diol Surfactant 0.1-2.0 Glycol Solvent 0.1-2.0 Defoamer0.05-1.0  Suspending agent 0.1-2.5 Glycol ether Solvent 0.2-4.0 MineralFiber 1.0-5.0 Acrylic Resin 35.0-50.0 Cellulosic Thickener 0.1-2.0Buffer 0.05-1.5  In can preservative 0.05-2.5  Associative Thickener0.05-10.0 Mildewcide/Algaecide 0.05-3.0  Flecks (Colored Chips)10.0-50.0 Defoamer 0.05-1.5  TOTAL 100%

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A coating composition comprising: a plurality offlakes present in an amount of 10 to 40 weight percent, the plurality offlakes having a maximum dimension less than 0.05 inches; a plurality ofinorganic fibers present in an amount from about 0.5 to 5 weightpercent; a thixotropic suspending agent present in an amount from about0.2 to 4 weight percent, the thixotropic suspending agent beinginsoluble in water; and a resin present in an amount from 10 to 25weight percent with the balance of the coating composition being water.2. The coating composition of claim 1 wherein the plurality of flakesincludes colored flakes.
 3. The coating composition of claim 1 whereinthe plurality of flakes include particles having an aspect ratio greaterthan
 10. 4. The coating composition of claim 1 wherein the thixotropicsuspending agent includes magnesium silicate.
 5. The coating compositionof claim 1 wherein the thixotropic suspending agent includesneedle-shaped particles having a length from about 1 to 5 microns and asurface area from about 100 to 500 m²/gram.
 6. The coating compositionof claim 1 wherein the thixotropic suspending agent includes sepioliteclay.
 7. The coating composition of claim 1 wherein the resin includesat least one acrylic resin.
 8. The coating composition of claim 1wherein water is present in an amount from about 10 to 30 weightpercent.
 9. The coating composition of claim 1 further including anadditive selected from the group consisting of pigments, solvents,thickeners, surfactants, defoamers, preservatives, buffers, andcombinations thereof.
 10. The coating composition of claim 9 wherein theadditive is present in an amount from about 0.1 to 10 weight percent.